1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a process cartridge and electrophotographic apparatus having the electrophotographic photosensitive member, and a method for producing an electrophotographic photosensitive member.
2. Description of the Related Art
Recently, research and development of electrophotographic photosensitive members (organic electrophotographic photosensitive members) using an organic photoconductive material have been performed actively.
The electrophotographic photosensitive member basically includes a support and a photosensitive layer formed on the support. Actually, however, in order to cover defects of the surface of the support, protect the photosensitive layer from electrical damage, improve charging properties, and improve charge injection prohibiting properties from the support to the photosensitive layer, a variety of layers is often provided between the support and the photosensitive layer.
Among the layers provided between the support and the photosensitive layer, as a layer provided to cover defects of the surface of the support, a layer containing a metal oxide particle is known. Usually, the layer containing a metal oxide particle has a higher conductivity than that of a layer containing no metal oxide particle (for example, volume resistivity of 1.0×108 to 5.0×1012 Ω·cm). Accordingly, even if the film thickness of the layer is increased, residual potential is hardly increased at the time of forming an image. For this reason, the defects of the surface of the support are easily covered. Such a highly conductive layer (hereinafter, referred to as a “conductive layer”) is provided between the support and the photosensitive layer to cover the defects of the surface of the support. Thereby, the tolerable range of the defects of the surface of the support is wider. As a result, the tolerable range of the support to be used is significantly wider, leading to an advantage in that productivity of the electrophotographic photosensitive member can be improved.
Japanese Patent Application Laid-Open No. 2004-151349 describes a technique in which a tin oxide particle doped with tantalum is used for an intermediate layer provided between a support and a barrier layer or a photosensitive layer. Japanese Patent Application Laid-Open No. H01-248158 and Japanese Patent Application Laid-Open No. H01-150150 describe a technique in which a tin oxide particle doped with niobium is used for a conductive layer or intermediate layer provided between a support and a photosensitive layer.
However, examination by the present inventors has revealed that if an image is repeatedly formed under a low temperature and low humidity environment using an electrophotographic photosensitive member employing the layer containing such a metal oxide particle as the conductive layer, then a leakage is likely to occur in the electrophotographic photosensitive member. The leakage is a phenomenon such that a portion of the electrophotographic photosensitive member locally breaks down, and excessive current flows in that portion. If the leakage occurs, the electrophotographic photosensitive member cannot be sufficiently charged, leading to image defects such as black dots and horizontal black stripes. The horizontal black stripes are black stripes that appear in the direction intersecting perpendicular to the rotational direction (circumferential direction) of the electrophotographic photosensitive member.